welcome back to another covid 19 video in this video i want to talk about
why so many covid 19 patients in the hospital are developing blood clots
and should we empirically give high doses of blood thinners to these patients who are in the hospital
so that's what we're going to tackle in this video but before i dive right in let's look at
a very interesting report that was published based on a study of patients who had severe covid disease
with ards this study was done based on patients in italy by the famous dr gatanoni who i think of as
the godfather of ards i mean this guy was publishing research articles about ards
while i was still in diapers let's start off by taking a quick look at what a normal ct scan of
the chest looks like black represents air and bone is white if the patient receives iv contrasts the
blood vessels will look white but the important thing to notice here is that the lungs are normal
now let's take a look at dr gatenoni's study what he found in his study of covid patients with
severe ards is that there seems to be two types of ards first take a look at the po2 and fio2
ratios of the patients in the study where it says 95 millimeters mercury and 84 millimeters mercury
these are extremely low levels of oxygen these numbers are telling us that these lungs in these
patients are having a very difficult time getting oxygen into their blood in half the patients in
the study the patients had the typical ards that we all know and hate which causes tons
of inflammation with fluid and debris filling the alveoli where the chest x-ray and the ct skin of
the lungs looks horrible this is depicted in the bottom ct scan let's take a closer look
look at all that grayish crap filling up the lungs that's not supposed to be there this type of ards
is what's known as the h-type h refers to high elastance meaning lots of stiffness in the lungs
these lungs are very stiff which does not bode well for lung function but then there's this
other type of ards which the other half of the patients in this study had these patients longs
have some of that grayish crap meaning there's some inflammation going on there but it's not as
much as you would expect given the degree of their hypoxemia in other words the oxygen levels are
far below what you would expect given the degree of inflammation that you're seeing in the lungs
this type of ards is known as the l-type meaning these patients have low elastance meaning their
lungs aren't very stiff so with this l phenotype there's something else besides inflammation that
is contributing towards their very low oxygen levels and it can only be one of two things or
a combination of these two things and that is one constriction of the arteries that deliver
blood to the lungs in other words pulmonary vasoconstriction and this is essentially pulmonary
hypertension meaning the pressure in these arteries is high this means that there's less
blood being sent to the lungs to pick up oxygen and this by itself can can cause low oxygen levels
the second thing is the development of clots within these arteries and capillaries and this
also impairs the ability of the lungs to get oxygen into the blood so what exactly are blood
clots and why are they so dangerous blood clots don't normally form in the body unless we have
bleeding for example if we cut our finger that's how we heal right the clot stops further bleeding
but sometimes some people form clots when they're not supposed to our blood besides being
mostly water is made up of a bunch of different proteins with different carbohydrates and fats
and these different chemicals interact with each other and all it takes is one piece of the puzzle
to be missing or abnormal to totally throw off the balance of either clotting too much or not
clotting enough for example hemophilia b these patients are missing a protein called factor ix
and that's why they bleed more than they should if it bleeds we can kill it no arnold that's
that's not what we're going for here but some people could have the opposite problem where they
clot too easily and they form unwanted blood clots which is what happens with for example
anti-phospholipid antibody syndrome and that's why these patients need to be on a blood thinner
so anti-phospholipid antibody syndrome is not only a mouthful but it's a pain in the ass because it
has a tendency to cause clots in both veins and arteries but guess what it's not the only cause of
abnormal clotting as there are hundreds of other medical conditions that can do the same thing such
as factor v liden and prothrombin gene mutation or antithrombin deficiency or protein c and protein
s deficiency regardless of the cause when blood clots do form they're most commonly in the deep
veins of our legs and sometimes our arms although they can form anywhere in our blood vessels when
blood clots form in our deep veins it's called deep vein thrombosis and the most common symptoms
are swelling and pain so deep vein thrombosis or dvt these are dangerous because they can break off
and travel to the heart and to the lungs and this is called pulmonary embolism which can be fatal
and there are plenty of people who die every year from pulmonary emboli sometimes the clot is so big
that it causes death within minutes thankfully not everyone who gets a blood clot in their lung
dies the most common symptoms of pulmonary emboli are shortness of breath chest pain and sometimes
cough they can also have lightheadedness and dizziness or even temporarily lose consciousness
and some people don't have any symptoms at all it usually depends on the size of the clot
sometimes clots can form in the arteries and cause a stroke or they can lodge in the coronary
arteries and cause a myocardial infarction meaning a heart attack or they can cut off
blood flow to a leg which is what happened to this doctor remember it's an aneurysm that clotted
leading to an infarction but this also happened to someone with covid 19 broadway star nick cordero
who unlike dr house had to have his leg amputated as a result and there are more reports of patients
presenting to the hospital not with typical covid 19 symptoms but symptoms of pulmonary emboli
this is this patient's ct scan of the chest they used iv contrast to do what's called an angiogram
so this is called a ct a of the chest or ct angio of the chest this is in the coronal plane meaning
in this view it's like you're facing the patient the contrast given makes the blood vessels light
up in bright white and when we see a dark spot where it's supposed to be bright white
that's how we identify the pulmonary embolism this patient also had bilateral ground glass opacities
or infiltrates if you will which is representative of fluid and or inflammation this patient was
admitted to the hospital was treated with a blood thinner and was eventually discharged from the
hospital so our blood clots at least part of the reason why some people with covid 19 are dying
I can tell you that the number of clotting problems my colleagues are seeing in icu across the country
all related to covid 19 is unprecedented but this isn't just a bunch of doctors and nurses that i
know who are reporting this there's actually a recent dutch study that found that 184 patients
in the icu with covid 19 pneumonia 20% of those patients were having clotting issues there is
also a similar study in wuhan where 25 percent of hospitalized covid patients had clots why and how
it starts coronavirus ii which invades the cells of the lungs specifically the type 2 alveoli how
is that causing blood clots to form in the body when someone has a severe case of covid 19 it's
causing a ton of inflammation within the lungs this inflammation is what's triggering the blood
clots to develop we knew this happens with ards even before covid 19 came around so if you saw
my video on how covid kills you may recall how i was talking about how with ards these patients
usually develop microthrombi meaning tiny clots that form in the tiny blood vessels in the lungs
and these microthrombi can combine to form bigger thrombi meaning bigger clots this
happens at least partly because of the cytokine storm that develops as a result of the infection
blood clots are also a concern with seriously ill people in general regardless of what illness
they have because these patients aren't moving much if at all and the lack of movement further
predisposes one to have in clots and that's the exact reason why when patients are admitted to
the intensive care unit we usually give them blood thinners unless there's a reason not to
for example if they have bleeding we don't want to give those patients blood thinners
but when we give these blood thinners we're giving them in prophylactic doses meaning the intention
is to reduce their risk of developing a clot in the first place but these prophylactic doses are
considered low dose and the chances of someone having severe bleeding from these small doses
is very small but the blood clots with covid 19 these are just a whole nother beast so how and why
is covid 19 causing more blood clots than usual like everything else in life it's complicated and
we still don't have it figured out check out this diagram actually don't it's really complicated
i'll summarize it for you long story short here the virus enters the alveolar cells
in the lungs using the ac2 receptor and once it does that it causes the cell to have less
h2 receptor on its surface this increases the amount of three things within the lungs
one inflammation two formation of clots and three constriction of blood vessels going to the lungs
meaning pulmonary vasoconstriction and guess what each and every one of these things by itself can
lead to low oxygen levels so you can imagine what that means when you have all three of these things
going on at the same time the way that oxygen gets into our blood from the alveoli it has to
diffuse from the alveoli to our capillaries but in those capillaries that encapsulate the alveoli
there's destruction there as well the inflammation in the cytokine storm is going on there in the
capillaries not just the alveoli the lining of these capillaries is called the endothelium
perhaps you remember this drawing from yours truly pay attention to the wall of the capillary this
lining is called the endothelium the cytokine storm causes destruction of the alveolus
and the endothelium and this this my friends is a trigger for clotting we knew this happens in ards
even before covid but guess what the virus that causes covid can actually invade the cells here
in the endothelium because these cells have ace2 receptors as well and that can cause
even more inflammation and more clotting and this study which looked at autopsies of two patients
found blood clots in the lungs and just beneath the surface of the skin the autopsy results showed
that within the lung there's lots of destruction of the capillaries that surround the alveoli
exactly what i was just talking about they also found blood clots beneath the skin's surface
on three living patients and in another published report in the new england journal medicine
there were three patients in the icu who had covid 19 and these three patients developed blood clots
that were significant enough to cause major blockages in blood vessels these three patients
were positive for anti-phospholipid antibodies more on that in a bit let's take a look at the
first case here it's a 69 year old male with a history of hypertension diabetes stroke who
comes in with fever cough shortness of breath and diarrhea also had a headache he developed
lower and lower oxygen levels to the point where he required intubation with mechanical ventilation
he also developed ischemia in both legs and in some of his fingers ischemia means he's not
getting enough blood flow to a certain part of his body and in his case it was to his fingers and to
his legs and when they did a ct skin of his head they found that he had multiple areas of strokes
when they did blood work on him he had low levels of platelets he had elevated prothrombin time and
elevated partial thromboplastin time he also had elevated levels of fibrinogen and d-dimer as it
turns out he was positive for anti-cardiolipin-iga antibodies as well as anti-beta-2 glycoprotein iga
and igg antibodies so what's the diagnosis that's right anti-phospholipid antibody syndrome
the other two patients in these case reports basically had the same story in the same diagnosis
these antibodies that i just mentioned are not in the blood for the vast majority of people
these antiphospholipid antibodies are bad because they attack the phospholipid proteins in our body
and if it's severe enough they can cause major clots to form in our blood vessels
so anti-phospholipid antibody syndrome it's a condition that depends on someone's genetics
but these antibodies can also arise transiently in patients with critical illness and various
infections so do all patients with covid 19 who have blood clots do they all have this transient
anti-phospholipid antibody syndrome we don't know yet so here's what we know so far even though
there are lots of gaps in our knowledge with this disease there's all the stuff that happens in the
lungs that we just talked about but also there's a cytokine storm that is triggered in the lungs that
can affect other organs in the body such as the heart the brain and the kidneys and as if that's
not bad enough just about all the other organs in the body have ace2 receptors such as the heart the
brain and the kidneys so inside the body covid is causing a category 10 hurricane in some people
about three to four percent of people who get the virus so besides looking at drugs that treat the
infection we also have to consider giving big doses of blood thinners to patients with severe
disease even if we're not able to diagnose them as having clots now some might say well doc why
can't you just diagnose them with clots easier said than done even during normal times but it's
especially harder to do this during a pandemic every test we do whether it's an ultrasound of
the legs looking for clots there whether it's getting a ct scan of the lungs looking for a clot
or ct the brain looking for a clot that's causing stroke there all of these things require more ppe
more potential exposure to the healthcare staff and sometimes doing these things have more risk to
the patient during certain tests for example like doing cta the chest where we give iv contrast
all these things have risks but even if we do all these tests and they come back negative there's
still the possibility of a false negative because no test has 100 sensitivity and 100 specificity
in other words no test is 100 accurate so there's going to be times where you have a
very sick patient with covid 19 in the icu and you don't know if they have blood clots
the question becomes should you give them a high dose blood thinner meaning should you treat them
as if they have blood clots not an easy question to answer because the risk of life-threatening
bleeding increases when you give them that high-dose blood thinner and based
on the studies i mentioned before it looks like about 25% of covid patients who are in the icu
do have clots so one clue that might make us more inclined to give high doses of blood thinners
would be to check their d dimer level in the blood because very high d-dimer levels are associated
with more severe covid disease the problem with that is just because someone has very high
d-dimer levels doesn't necessarily mean that they have clots because it's a very non-specific test
we know that there are a thousand causes of high d-dimer levels because inflammation in general is
a very well-known cause i mentioned before that even before covid 19 we knew that ards causes
these microthrombin and that's why in the past there have been studies that looked at giving
these patients different forms of blood thinners these patients didn't benefit from the blood
thinners as they actually had more bleeding and ultimately had worse outcomes but these studies
don't apply necessarily to covid 19 ards because this ards is a whole nother animal also the blood
thinners in these studies were not the typical blood thinners that we use today so that's another
reason unfortunately because this disease is so mysterious and so new with relatively few
high quality studies doctors don't have much to go on when it comes to treating these patients
we're going to have to make difficult decisions especially when it comes to giving a high dose
of a blood thinner in the icu if we see that the patient has a blood clot then the answer is easy
give them a blood thinner as long as they don't have bleeding issues but if we don't see blood
clots it's a difficult decision that will have to be made on a case-by-case basis also something a
lot of people want to know is there something that you can do to reduce your risk of developing blood
clots the biggest thing that people in general can do is to stay active meaning minimize your
time sitting in a chair that's one factor that makes people more prone to developing clots
so exercise is great but even if you can't exercise even just walking around the room
or doing some stretching exercises or even jumping jacks if you can other than
that you're going to want to take your doctor's advice on how to optimize your
health so that's all for this video hope you enjoyed it and i'll see you in the next one